Photoluminescence-tunable carbon nanodots: surface-state energy-gap tuning.

The photoluminescence of carbon nanodots (C-dots) can be tuned by changing their surface chemistry or size because the photoluminescence is a function of the surface-state electronic transitions. Increasing the degree of surface oxidation leads to a narrowing of the energy gap of the surface; meanwhile, larger C-dots with an extensive π-electron system, which can couple with surface electronic states, can also lead to a narrowing of the energy gap of the surface states.